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   Sharma, Aniket; Medeiros, Lia; Wong, George N; Chan, Chi-kwan; Halevi, Goni; Mullen, Patrick D; Stone, James M (May 2025, The Astrophysical Journal)

   Abstract We introduceMahakala, aPython-based, modular, radiative ray-tracing code for curved spacetimes. We employ Google’sJAXframework for accelerated automatic differentiation, which can efficiently compute Christoffel symbols directly from the metric, allowing the user to easily and quickly simulate photon trajectories through non-Kerr spacetimes.JAXalso enablesMahakalato run in parallel on both CPUs and GPUs.Mahakalanatively uses the Cartesian Kerr–Schild coordinate system, which avoids numerical issues caused by the pole in spherical coordinate systems. We demonstrateMahakala’s capabilities by simulating 1.3 mm wavelength images (the wavelength of Event Horizon Telescope observations) of general relativistic magnetohydrodynamic simulations of low-accretion rate supermassive black holes. The modular nature ofMahakalaallows us to quantitatively explore how different regions of the flow influence different image features. We show that most of the emission seen in 1.3 mm images originates close to the black hole and peaks near the photon orbit. We also quantify the relative contribution of the disk, forward jet, and counterjet to 1.3 mm images. 

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4. PyQMC : An all-Python real-space quantum Monte Carlo module in PySCF

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   Wheeler, William A.; Pathak, Shivesh; Kleiner, Kevin G.; Yuan, Shunyue; Rodrigues, João N. B.; Lorsung, Cooper; Krongchon, Kittithat; Chang, Yueqing; Zhou, Yiqing; Busemeyer, Brian; et al (March 2023, The Journal of Chemical Physics)

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5. The evolution of galaxy intrinsic alignments in the MassiveBlackII universe

   https://doi.org/10.1093/mnras/stz3240  

   Bhowmick, Aklant K; Chen, Yingzhang; Tenneti, Ananth; Di Matteo, Tiziana; Mandelbaum, Rachel (January 2020, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT We investigate the redshift evolution of the intrinsic alignments (IAs) of galaxies in the MassiveBlackII (MBII) simulation. We select galaxy samples above fixed subhalo mass cuts ($$M_h\gt 10^{11,12,13}\,\mathrm{M}_{\odot }\, h^{-1}$$) at z = 0.6 and trace their progenitors to z = 3 along their merger trees. Dark matter components of z = 0.6 galaxies are more spherical than their progenitors while stellar matter components tend to be less spherical than their progenitors. The distribution of the galaxy–subhalo misalignment angle peaks at ∼10 deg with a mild increase with time. The evolution of the ellipticity–direction (ED) correlation amplitude ω(r) of galaxies (which quantifies the tendency of galaxies to preferentially point towards surrounding matter overdensities) is governed by the evolution in the alignment of underlying dark matter (DM) subhaloes to the matter density of field, as well as the alignment between galaxies and their DM subhaloes. At scales $$\sim 1~\mathrm{Mpc}\, h^{-1}$$, the alignment between DM subhaloes and matter overdensity gets suppressed with time, whereas the alignment between galaxies and DM subhaloes is enhanced. These competing tendencies lead to a complex redshift evolution of ω(r) for galaxies at $$\sim 1~\mathrm{Mpc}\, h^{-1}$$. At scales $$\gt 1~\mathrm{Mpc}\, h^{-1}$$, alignment between DM subhaloes and matter overdensity does not evolve significantly; the evolution of the galaxy–subhalo misalignment therefore leads to an increase in ω(r) for galaxies by a factor of ∼4 from z = 3 to 0.6 at scales $$\gt 1~\mathrm{Mpc}\, h^{-1}$$. The balance between competing physical effects is scale dependent, leading to different conclusions at much smaller scales ($$\sim 0.1~\mathrm{Mpc}\, h^{-1}$$). 

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